SFAIK, a lever filler doesn't have a spring, but it has a "springy" J bar. You can rinse the insides if it is inky until it runs clear, but it is best to dry them thoroughly as the J bar and sometimes the lever and lever box can rust. Ditto for the cap which can also have an inner cap with some rust-prone metal and the clip might rust as well. Only part of pens I soak are nibs, feeds, and sections and sometimes, the lower end of plastic barrels to try to clean the ink off the threads (if they are inky).

What doyou mean by cleaning?
Do you want to clean the inside of a barrel?
Soaking of barrels and sections are in general not advised unless there is a specific reason. If you want to clean the inner surface then a long q-tip with a weak solution of ammonia will work on most cases.
Please give us more information (types of pens and condition) and I will try to answer.

I will post descriptions of the pens. I would be willing to bet that these pens are either ten cents in some discount store and I am the biggest jerk for purchasing them OR they are worth billions and I will be congratulated here for my buying saavy. In any event, I can't post now since that would involve turning on a light and since the entire house is asleep, I would be in serious danger LOL..so, until tomorrow....

Since the birds are now singing and the sun is up, here are the descriptions of the pens:
1- Parker 21 Silver colored cap, dark green barrel
2- Eversharp with tags still on - one tag reads: model 707 $3.75. the other tag reads medium. Lever fill. nib 14K barrel dark green gold colored cap
3- Lord Baltimore written on clip. pen almost 5 1/2" long. Cap has wide gold colored band starting beneath clip with 7 lines on it completely encircling the band. Cap is flat on three sides so the pen can't roll off a desk. Nib reads: Veri smooth Made in U.S.A. lever fill. color of entire pen is a periwinkle-grey color. Clip is attached to top of cap with button
4- Stratford 5/14" long. Black Name inscribed on gold colored clip. Clip attached to top of cap with button. Nib reads: special alloy made in USA. Pen fills by means of a screw off cap and button-type device (is this piston?).
5 - No name pen. 4 1/4" long. Made of very lightweight material - swirly brown and dark brown iridescent type design. Top of cap has small indentation. Something is definitely missing -either a jewel or a clip? No clip on pen Small gold colored band around bottom of cap with tiny lines inscribed in the center almost like lower case i's sans the dots. When viewed through a loupe, the design on the pen is composed of thousands of gold lines that appear as though someone took a comb, dipped it in gold ink and ran it in random lines across a black background. Nib inscribed Epenco NY. Lever fill.
6- Sheaffer snorkel- burgundy colored, gold band around bottom of cap. White dot on top of clip. Nib reads: Sheaffer's Reg. U.S. Pat. Office Made in U.S.A. 14 k. There is no snorkel nor a place for one on the nib.
7- Metal green marbled FP with gold colored clip inscribed: Eagle Pencil Co. U.S.A. Nib reads Marvel Pen and has a heart shaped hole. Lever fill.

All of these pens are fountain pens. I haven't the slightest idea of their values or how to either clean them or repair them. The nibs are all filthy with years of grit and staining. The Parker 21 we sadly discovered when we took it out into the light has a crack running from the nib right down to the silver band through which ink is leaking (pen was not inked obviously when we purchased it). We think there was a tag over this area which explains our stupidity...won't happen again I assure you.

1- Parker 21 -----------------------------------------------------If there is no crack in the hood it might make a good writer. Otherwise throw it in the parts bin . Anyway it may be a good pen to practice cleaning or nib smooth etc.To clean flash the section by filling/emptying multiple times until the water runs out clear.

2- Eversharp model 707 $3.75. -----------------------------------------------------99% this is an Eversharp Symphony. It probably works without doing anything. With a soft cloth remove the dirt/dust. Do not overdo it on the cap - it may scratch. Use a plastic polishing compound (like this from Thyphon's catalog) for the body. Check if it fills with water. If it does it can probably write unless the nib is bent/broken. They are usually excellent writers.

3- Lord Baltimore-----------------------------------------------------I usually keep the pressure bar and the feed from such pens. You might want to use it for practice. But you may want to practice repair on it since it is an inexpensive sample.

5 - No name pen. -----------------------------------------------------See 3. Some people like this pattern.

6- Sheaffer snorkel-----------------------------------------------------This is probably a touchdown. Relatively easy repair but you need a proper sac. Flash the section with an earbulb syringe or equivalent. Use simichrome for the cap and simichrome or a plastic polishing compound for the body.

Thank you for your input. Interestingly enough, the Lord Baltimore and the Stratford are wonderful writers. Too bad about the 21..it really makes me wonder where my mind was when I was looking at this pen...grr...I think I will try the ultrasonic.

5- epenco is a contraction of eagle pen/pencil company, ny. while not a first tier company, the pens, like many others of the golden era, can be very good and servicable writers when restored.
as mentioned, i would refrain from introducing liquids to clean the inside of a pen unless you have dismantled it and plan a thorough job of it, including sac replacement. i usually do this as a matter of course unless i know that it has already been done by someone whose work i trust. be sure all is bone dry before putting it all back together.